Two-way transparent display

ABSTRACT

A display that contains a sparse array of light-emitting diodes (LEDs), system, and method of fabrication are disclosed. The display includes a panel having at least one tile configured to display information. The panel is disposed within or on a transparent material. Each tile includes an array of LEDs, which have a uniform distance therebetween such that light from the array is viewable on opposing sides of the panel while providing visibility through the panel. A darkening layer on at least one side of the panel provides selectable darkening to block the light from exiting the at least one side of the panel.

PRIORITY

This patent application claims the benefit of priority to U.S.Provisional Patent Application Ser. No. 63/352,517, filed on Jun. 15,2022, and U.S. Provisional Patent Application 63/420,872, filed on Oct.31, 2022, each of which is hereby incorporated by reference herein inits entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to sparse light-emitting diode (LED)arrays, systems, and applications.

BACKGROUND OF THE DISCLOSURE

LEDs provide an efficient and relatively smaller source of lightcompared to conventional light sources. The use of LEDs has evolved fromsystems that provide purely lighting to more complicated systems thatuse light in various ways other than merely to provide illumination ofan area. Consequently, there is ongoing effort to improve technologythat uses LED arrays, as well as find additional uses for LED arrays.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional side view of an example of a lightsource.

FIG. 2 shows a block diagram of an example of a visualization system,which can include the light source of FIG. 1 .

FIGS. 3 and 4 show side-view drawings of the light source of FIG. 1 invarious stages of assembly.

FIG. 5A-5D each illustrate a cross-sectional view of an LED of a sparsearray, in accordance with some examples.

FIG. 6 shows a top view of an example panel in accordance with variousembodiments of the disclosed subject-matter.

FIG. 7 illustrates an example of a panel with a single tile inaccordance with various embodiments of the disclosed subject-matter.

FIGS. 8A-8B illustrate an example of a panel with multiple display tilesin accordance with various embodiments of the disclosed subject-matter.

FIGS. 9A and 9B show examples of a sparse LED array arrangement inaccordance with various embodiments of the disclosed subject-matter.

FIG. 10 shows an example display in accordance with various embodimentsof the disclosed subject-matter.

FIG. 11 shows an example system in accordance with various embodimentsof the disclosed subject-matter.

FIG. 12 illustrates an example of a general device in accordance withsome embodiments.

FIGS. 13A-13G process operations of fabricating the sparse array inaccordance with some embodiments.

FIG. 14 illustrates an example of a method of fabricating the sparsearray in accordance with the process operations shown in FIGS. 13A-13G.

FIG. 15 illustrate an example of a process of providing improvedcontrast in accordance with some embodiments.

FIG. 16 shows an example display stack in accordance with variousembodiments of the disclosed subject-matter.

Corresponding reference characters indicate corresponding partsthroughout the several views. Elements in the drawings are notnecessarily drawn to scale. The configurations shown in the drawings aremerely examples and should not be construed as limiting in any manner.

DETAILED DESCRIPTION

The use of the transparent displays, described herein, which are enabledby microLEDs, may be able to expand capability in user experience byproviding signage, interactive menus, entrance criteria, publicinformation, and many other cases. The user experience may be enhanced,for example, by allowing for rich augmented reality (AR) and/or virtualreality (VR) experiences, entertainment, and many other cases.Multi-display functionality may be provided with the same display,enabled by effectively being able to produce similar quality images onboth of its sides, therefore effectively creating a two-way display,which may be used in a variety of consumer, industrial, and commercialsettings.

For the purposes of this document, the term “micro-LED” is intended tobe synonymous with an LED of a sparse array of LEDs as defined herein.There is ongoing effort to improve micro-LED display technology. Forexample, displays, such as direct-view displays and projection displays,can use micro-LEDs to improve efficiency and increase brightness.

In a direct-view micro-LED display, the LEDs may occupy a relativelysmall fraction of the display area. Because most of the display area isunaffected by the LEDs, the LEDs may not substantially alter the opticalproperties of the surface on which they are assembled. For example, ablack surface may remain black in the presence of LEDs mounted on theblack surface. Similarly, a reflective surface may remain reflective inthe presence of LEDs mounted on the reflective surface. Other examplesand optical surface properties can also be used.

In some examples, the micro-LEDs can be assembled onto a transparentand/or flexible substrate. The transparent flexible substrate can thenbe laminated onto a substrate that has desired optical properties, suchas being reflective, and so forth. Using the transparent flexiblesubstrate in this manner can allow micro-LEDs to be applied to a curvedor irregularly shaped substrate, which may not be compatible withmicro-LED assembly technologies that use a rigid, flat substrate, suchas a wafer.

In some examples, the flexible substrate can be laminated LED-side downonto the substrate, using a transparent adhesive that has sufficientthickness to encapsulate the micro-LEDs. For these examples and others,the transparent substrate and adhesive can also function as a barrierthat can protect the micro-LEDs from the environment. Because thetransparent substrate can provide protection for the micro-LEDs, thetransparent substrate can reduce or eliminate the need to use anadditional transparent cover or protection layer to provide theprotection for the micro-LEDs.

FIG. 1 shows a cross-sectional side view of an example of a light source100. The light source 100 can include a sparse array of LEDs 102 (e.g.,“micro-LEDs”) disposed on a transparent flexible substrate 104, and arigid substrate 106 adhered to the transparent flexible substrate 104with an adhesive layer 108 such that the sparse array of LEDs 102 islocated between the rigid substrate 106 and the transparent flexiblesubstrate 104. The sparse array of LEDs 102 can be encapsulated in theadhesive 110 of the adhesive layer 108.

The transparent flexible substrate 104 can be a polymer sheet with arelatively high transmittance, or, equivalently, relatively low lossesdue to absorption and scattering in the visible portion of theelectromagnetic spectrum, such as between wavelengths of about 400 nmand about 700 nm. Suitable materials for the transparent flexiblesubstrate 104 can include clear polyimide (PI), polyethylene naphthalate(PEN), polyethylene terephthalate (PET) and others. The transparentflexible substrate 104 can have a thickness between about 20 μm andabout 200 μm, although a thickness outside this range of thicknesses canalso be used.

The sparse array of LEDs 102 can be disposed on the transparent flexiblesubstrate 104. For the purposes of this document, the term sparse isintended to signify that a light-producing surface area of the array isless, or significantly less, than a total surface area of the array. Forexample, a fill factor of the array (e.g., a ratio of light-producingsurface area to full surface area) can be less than or equal to aspecified threshold, such as 10%, 5%, 4%, 3%, 2%, 1%, or anothersuitable threshold. As a specific example, the LEDs 102 can be arrangedin a rectangular array, with center-to-center spacing along onedimension denoted by spacing x. Each LED 102 can have a light-producingarea sized along the one dimension by size s. The ratio of s divided byx can be less than or equal to 0.1. In an orthogonal dimension, asimilar ratio applies, with the linear size of a light-producing areabeing less than or equal to one-tenth the linear center-to-centerspacing of the LEDs 102. Combining the two linear dimensions, thesurface area of the light-producing areas of the LEDs 102 is less thanor equal to 1% of the surface area of the array. In some examples, thelight-producing area of each LED can be smaller than 200 μm on a side.In some examples, the light-producing area of each LED can be smallerthan 50 μm on a side. Electrical traces can be deposited on thetransparent flexible substrate 104 to electrically power (e.g., carrycurrent to and from) the LEDs 102. In some examples, the electricaltraces can be metal traces that are narrow enough to be invisible undertypical viewing conditions. In some examples the electrical traces canbe formed from one or more transparent electrically conductivematerials, such as indium tin oxide (ITO). Note that the terms“substantially transparent” and “transparent” are used interchangeablyherein to refer to materials (such as metal oxides or very thin metals)through which light from the microLEDs passes without beingsubstantially (more than a few percent) absorbed or reflected. Each ofthese examples of electrical traces (e.g., narrow metal traces andtransparent electrically conductive materials) may be considered toprovide transparent electrical traces.

In some examples, the sparse array of LEDs 102 can include two or moreLEDs 102 that emit light at a same wavelength (or color). In someexamples, the sparse array of LEDs 102 can include LEDs 102 that allemit light at a same wavelength. For example, a device, such as adisplay, can include a sparse array of LEDs 102 that all emit red light,a sparse array of LEDs 102 that all emit green light, and a sparse arrayof LEDs 102 that all emit blue light. In some examples, the sparse arrayof LEDs 102 can include two or more LEDs 102 that emit light atdifferent wavelengths. For example, a device, such as a display, caninclude a sparse array of LEDs 102 in which some LEDs 102 emit redlight, some LEDs 102 emit green light, and some LEDs 102 can emit bluelight. The red, green, and blue LEDs 102 can be arranged in repeatingclusters, with each cluster forming a color pixel of the device. In someexamples, the sparse array of LEDs 102 can include at least one LED thatemits light at a visible wavelength (e.g., between about 400 nm andabout 700 nm). In some examples, the sparse array of LEDs 102 caninclude at least one LED that emits light at an infrared wavelength(e.g., greater than about 700 nm). Such infrared wavelengths can be usedfor biometric sensing or other sensing techniques.

Because the sparse array of LEDs 102, including the light-emitting areaof the LEDs 102, the corresponding electrical traces, and anycorresponding circuitry, can have a relatively small fill factor, mostof the surface area of the sparse array of LEDs 102 can be transparent.For example, light incident on the sparse array of LEDs 102, eitherincident from the transparent flexible substrate 104 or incident on thetransparent flexible substrate 104, mostly passes through the sparsearray of LEDs 102, with only a relatively small fraction being blockedby the light-emitting areas and electrical traces of the sparse array ofLEDs 102.

As a result, the sparse array of LEDs 102 can produce light on a surfaceand/or an optical element that has an additional function, such as onthe rigid substrate 106, described below. For example, the surfaceand/or optical element can include a reflector that has a specifiedvalue of reflectance. As another example, the surface and/or opticalelement can include a spectral filter that has a specified reflectance,transmittance, or absorptance at one or more specified wavelengths.Other suitable functions can also be used.

The rigid substrate 106 can be adhered to the transparent flexiblesubstrate 104. In some examples, the rigid substrate 106 can betransparent. Suitable applications for a transparent rigid substrate 106can include a building window, a heads-up display, an augmented realityheadset, and others. Suitable transparent materials for a transparentrigid substrate 106 can include glass, laminated glass, polycarbonate,or an engineering plastic such as poly(methyl methacrylate) (PMMA).

In some examples, the rigid substrate 106 can be reflective. In someexamples, the rigid surface can be specularly reflective (e.g., can havea relatively smooth reflective surface that causes relatively littlescattering or diffusion upon reflection). Suitable applications for areflective rigid substrate 106 can include a mirror, such as a vehicularrear-view mirror or side-view mirror that can display information.Specifically, the specularly reflective surface of the rigid substrate106 can perform the function of reflecting light from the rear of avehicle, while the sparse array of LEDs 102 can display informationsuperimposed on the reflected light.

In some examples, the rigid substrate 106 can be protective and/ordecorative, such as a case material of a mobile device, such as a smartphone. The rigid substrate 106 can include other suitable opticalproperties and perform other suitable functions as well.

The rigid substrate 106 can be flat (e.g., substantially flat) orcurved. Curved substrates can be used in vehicle windshields, augmentedreality headsets, wearables, or other suitable devices. In someexamples, the rigid substrate 106 is formed as a single unitary body. Inother examples, the rigid substrate 106 can include multiple rigidsubstrate elements. For example, multiple rigid substrate elements canbe used to create a folding display in a smartphone or other mobiledevice. Custom tooling can support such curved substrates in thelamination process, described below.

The adhesive can adhere the rigid substrate 106 to the transparentflexible substrate 104. In some examples, the adhesive can be formed asan adhesive layer 108 such that the sparse array of LEDs 102 is locatedbetween the rigid substrate 106 and the transparent flexible substrate104. Other suitable configurations can also be used. Suitable materialsfor the adhesive of the adhesive layer 108 can include silicone, epoxysilicone, an acrylic film, an epoxy film, and others.

In some examples, the adhesive of the adhesive layer 108 can be formedfrom a material having a refractive index that can match orsubstantially match a refractive index of the transparent flexiblesubstrate 104 and/or the rigid substrate 106 or can fall betweenrefractive indices of the transparent flexible substrate 104 and therigid substrate 106. Selecting a refractive index in this manner canreduce or eliminate reflections at the interface between the adhesivelayer 108 and the transparent flexible substrate 104 and/or at theinterface between the adhesive layer 108 and the rigid substrate 106.For example, the adhesive of the adhesive layer 108 can be formed from amaterial having a refractive index between about 1.4 and about 1.7.Using a refractive index in the range of about 1.4 to about 1.7 canreduce unwanted reflections between the adhesive layer 108 and thetransparent flexible substrate 104 and unwanted reflections between theadhesive layer 108 and the rigid substrate 106. Optional thin-filmanti-reflection coatings can also be used to help reduce or eliminateunwanted reflections at one or more interfaces between adjacentdiffering materials or between a material and air.

In some examples, the adhesive layer 108 can fully encapsulate thesparse array of LEDs 102. By fully encapsulating the sparse array ofLEDs 102, the adhesive layer 108 can protect the sparse array of LEDs102 from the environment and can form a smooth, unbroken interface withthe rigid substrate 106. To fully encapsulate the sparse array of LEDs102, the adhesive of the adhesive layer 108 can have a resin viscositythat is low enough such that the adhesive flows around the LEDs 102 asthe adhesive is deposited. In addition, to fully encapsulate the sparsearray of LEDs 102, the adhesive layer 108 can be thick enough to fullycover the topography of the sparse array of LEDs 102.

FIG. 2 shows a block diagram of an example of a visualization system 10,which can include the light source 100 of FIG. 1 . The visualizationsystem 10 can include a wearable housing 12, such as a headset orgoggles. The housing 12 can mechanically support and house the elementsdetailed below. In some examples, one or more of the elements detailedbelow can be included in one or more additional housings that can beseparate from the wearable housing 12 and couplable to the wearablehousing 12 wirelessly and/or via a wired connection. For example, aseparate housing can reduce the weight of wearable goggles, such as byincluding batteries, radios, and other elements. The housing 12 caninclude one or more batteries 14, which can electrically power any orall of the elements detailed below. The housing 12 can include circuitrythat can electrically couple to an external power supply, such as a walloutlet, to recharge the batteries 14. The housing 12 can include one ormore radios 16 to communicate wirelessly with a server or network via asuitable protocol, such as WiFi.

The visualization system 10 can include one or more sensors 18, such asoptical sensors, audio sensors, tactile sensors, thermal sensors,gyroscopic sensors, time-of-flight sensors, triangulation-based sensors,and others. In some examples, one or more of the sensors can sense alocation, a position, and/or an orientation of a user. In some examples,one or more of the sensors 18 can produce a sensor signal in response tothe sensed location, position, and/or orientation. The sensor signal caninclude sensor data that corresponds to a sensed location, position,and/or orientation. For example, the sensor data can include a depth mapof the surroundings. In some examples, such as for an augmented realitysystem, one or more of the sensors 18 can capture a real-time videoimage of the surroundings proximate a user.

The visualization system 10 can include one or more video generationprocessors 20. The one or more video generation processors 20 canreceive, from a server and/or a storage medium, scene data thatrepresents a three-dimensional scene, such as a set of positioncoordinates for objects in the scene or a depth map of the scene. Theone or more video generation processors 20 can receive one or moresensor signals from the one or more sensors 18. In response to the scenedata, which represents the surroundings, and at least one sensor signal,which represents the location and/or orientation of the user withrespect to the surroundings, the one or more video generation processors20 can generate at least one video signal that corresponds to a view ofthe scene. In some examples, the one or more video generation processors20 can generate two video signals, one for each eye of the user, thatrepresent a view of the scene from a point of view of the left eye andthe right eye of the user, respectively. In some examples, the one ormore video generation processors 20 can generate more than two videosignals and combine the video signals to provide one video signal forboth eyes, two video signals for the two eyes, or other combinations.

The visualization system 10 can include one or more light sources 22(such as the light source 100 of FIG. 1 ) that can provide light for adisplay of the visualization system 10. Suitable light sources 22 caninclude a light-emitting diode, a monolithic light-emitting diode, aplurality of light-emitting diodes, an array of light-emitting diodes,an array of light-emitting diodes disposed on a common substrate, asegmented light-emitting diode that is disposed on a single substrateand has light-emitting diode elements that are individually addressableand controllable (and/or controllable in groups and/or subsets), anarray of micro-light-emitting diodes (microLEDs), and others. In someexamples, one or more of the light sources 22 can include a sparse arrayof LEDs disposed on a transparent flexible substrate, and a rigidsubstrate adhered to the transparent flexible substrate with an adhesivelayer such that the sparse array of LEDs is located between the rigidsubstrate and the transparent flexible substrate.

A light-emitting diode can be white-light light-emitting diode. Forexample, a white-light light-emitting diode can emit excitation light,such as blue light or violet light. The white-light light-emitting diodecan include one or more phosphors that can absorb some or all of theexcitation light and can, in response, emit phosphor light, such asyellow light, that has a wavelength greater than a wavelength of theexcitation light.

The one or more light sources 22 can include light-producing elementshaving different colors or wavelengths. For example, a light source caninclude a red light-emitting diode that can emit red light, a greenlight-emitting diode that can emit green light, and a bluelight-emitting diode that can emit blue right. The red, green, and bluelight combine in specified ratios to produce any suitable color that isvisually perceptible in a visible portion of the electromagneticspectrum.

The visualization system 10 can include one or more modulators 24. Themodulators 24 can be implemented in one of at least two configurations.

In a first configuration, the modulators 24 can include circuitry thatcan modulate the light sources 22 directly. For example, the lightsources 22 can include an array of light-emitting diodes, and themodulators 24 can directly modulate the electrical power, electricalvoltage, and/or electrical current directed to each light-emitting diodein the array to form modulated light. The modulation can be performed inan analog manner and/or a digital manner. In some examples, the lightsources 22 can include an array of red light-emitting diodes, an arrayof green light-emitting diodes, and an array of blue light-emittingdiodes, and the modulators 24 can directly modulate the redlight-emitting diodes, the green light-emitting diodes, and the bluelight-emitting diodes to form the modulated light to produce a specifiedimage.

In a second configuration, the modulators 24 can include a modulationpanel, such as a liquid crystal panel. The light sources 22 can produceuniform illumination, or nearly uniform illumination, to illuminate themodulation panel. The modulation panel can include pixels. Each pixelcan selectively attenuate a respective portion of the modulation panelarea in response to an electrical modulation signal to form themodulated light. In some examples, the modulators 24 can includemultiple modulation panels that can modulate different colors of light.For example, the modulators 24 can include a red modulation panel thatcan attenuate red light from a red light source such as a redlight-emitting diode, a green modulation panel that can attenuate greenlight from a green light source such as a green light-emitting diode,and a blue modulation panel that can attenuate blue light from a bluelight source such as a blue light-emitting diode.

In some examples of the second configuration, the modulators 24 canreceive uniform white light or nearly uniform white light from a whitelight source, such as a white-light light-emitting diode. The modulationpanel can include wavelength-selective filters on each pixel of themodulation panel. The panel pixels can be arranged in groups (such asgroups of three or four), where each group can form a pixel of a colorimage. For example, each group can include a panel pixel with a redcolor filter, a panel pixel with a green color filter, and a panel pixelwith a blue color filter. Other suitable configurations can also beused.

The visualization system 10 can include one or more modulationprocessors 26, which can receive a video signal, such as from the one ormore video generation processors 20, and, in response, can produce anelectrical modulation signal. For configurations in which the modulators24 directly modulate the light sources 22, the electrical modulationsignal can drive the light sources 24. For configurations in which themodulators 24 include a modulation panel, the electrical modulationsignal can drive the modulation panel.

The visualization system 10 can include one or more beam combiners 28(also known as beam splitters 28), which can combine light beams ofdifferent colors to form a single multi-color beam. For configurationsin which the light sources 22 can include multiple light-emitting diodesof different colors, the visualization system 10 can include one or morewavelength-sensitive (e.g., dichroic) beam splitters 28 that can combinethe light of different colors to form a single multi-color beam.

The visualization system 10 can direct the modulated light toward theeyes of the viewer in one of at least two configurations. In a firstconfiguration, the visualization system 10 can function as a projector,and can include suitable projection optics 30 that can project themodulated light onto one or more screens 32. The screens 32 can belocated a suitable distance from an eye of the user. The visualizationsystem 10 can optionally include one or more lenses 34 that can locate avirtual image of a screen 32 at a suitable distance from the eye, suchas a close-focus distance, such as 500 mm, 750 mm, or another suitabledistance. In some examples, the visualization system 10 can include asingle screen 32, such that the modulated light can be directed towardboth eyes of the user. In some examples, the visualization system 10 caninclude two screens 32, such that the modulated light from each screen32 can be directed toward a respective eye of the user. In someexamples, the visualization system 10 can include more than two screens32. In a second configuration, the visualization system 10 can directthe modulated light directly into one or both eyes of a viewer. Forexample, the projection optics 30 can form an image on a retina of aneye of the user, or an image on each retina of the two eyes of the user.

For some configurations of augmented reality systems, the visualizationsystem 10 can include an at least partially transparent display, suchthat a user can view the user's surroundings through the display. Forsuch configurations, the augmented reality system can produce modulatedlight that corresponds to the augmentation of the surroundings, ratherthan the surroundings itself. For example, in the example of a retailershowing a chair, the augmented reality system can direct modulatedlight, corresponding to the chair but not the rest of the room, toward ascreen or toward an eye of a user.

FIGS. 3 and 4 show side-view drawings of the light source 100 of FIG. 1in various stages of assembly. Assembling the light source 100 in thismanner can help avoid air occlusions, which can degrade the appearanceand optical performance of the finished device. Other assemblytechniques can also be used.

In FIG. 3 , a sparse array of LEDs 102 has been disposed (e.g., mounted,grown, deposited, or otherwise formed) on the transparent flexiblesubstrate 104. The transparent flexible substrate 104 has been removablymounted in or on a frame 302. Lamination tooling 304 can advance theframe 302 toward an adhesive layer 306 that has been deposited on asupport film 308. Alternatively, the lamination tooling 304 can advancethe adhesive layer 306 toward the frame 302, or advance both toward eachother. The sparse array of LEDs 102 will contact the adhesive layer 306,which has been deposited on the support film 308. The adhesive of theadhesive layer 306 can be in solid form at room temperature. Theadhesive has been coated on the support film 308 and has been covered bya cover film (not shown). A vacuum laminator with a temperature rangethat allows the adhesive to flow and conformally cover the LED arraytopography can laminate the adhesive layer 306 onto the sparse array ofLEDs 102 to encapsulate the sparse array of LEDs 102 in the adhesivelayer 108. After lamination, the support film 308 can then be removed.

In FIG. 4 , the lamination tooling 404 (optionally the same laminationtooling 304 as in FIG. 3 ) can advance the transparent flexiblesubstrate 104 and the adhesive layer 108, with the sparse array of LEDs102 encapsulated in the adhesive layer 108, toward the rigid substrate106. Alternatively, the lamination tooling 404 can advance the rigidsubstrate 106 toward the transparent flexible substrate 104 and theadhesive layer 108, or advance both toward each other. The laminationtooling can laminate the adhesive layer 108, with the sparse array ofLEDs 102 encapsulated in the adhesive layer 108, onto the rigidsubstrate 106. After the adhesive layer 108 has been laminated onto therigid substrate 106, the full layered structure can be subjected to atemperature cycle, exposure to ultraviolet light, or other suitablecuring technique to cure the adhesive.

In the examples described above, the transparent flexible substrate 104has been laminated with the LED side facing the rigid substrate 106,such that the LEDs 102 are located between the two substrates andencapsulated by the adhesive. Alternatively, the transparent flexiblesubstrate 104 can be laminated with the LED side facing away from therigid substrate 106, such that the LEDs 102 are exposed, and thetransparent flexible substrate 104 is located between the exposed LEDs102 and the rigid substrate 106.

In some examples, additional components can be assembled onto thetransparent flexible substrate, such as integrated circuits (ICs),micro-ICs, or transistors for display backplanes. Moreover, additionallayers may be integrated into a device to form a capacitive or resistivetouchscreen.

In some embodiments, an LED includes multiple semiconductor layers grownon a substrate (e.g., a sapphire substrate) that are to be fabricatedinto pixels. The substrate may be any substrate, such as sapphire,capable of having epitaxial layers grown thereon. The substrate may havepatterns on which the epitaxial layers are grown. The pixels may beformed from gallium nitride (GaN), having an n-type semiconductoradjacent to the substrate, a p-type semiconductor, and an active regionbetween the n-type semiconductor and the p-type semiconductor. Theactive region may be, for example, a multiple quantum well structure inwhich light is generated for emission from the pixels. After processing,the substrate may be removed in some embodiments.

Before etching of the epitaxial GaN layers, die layers of chip-scalepackages (CSP) allowing uniform current distribution and opticalcoupling may be deposited or otherwise formed. For example, uniformcurrent injection in the p-type semiconductor may be obtained bydepositing a transparent conductive oxide (TCO) layer such as indium tinoxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or tin oxide(SnO) on the p-type semiconductor. Each of these TCO layers may beconsidered to be a transparent coating.

FIG. 5A illustrates a cross-sectional view of an LED 500 a of a sparsearray, in accordance with some examples. The LED 500 a may contain anepitaxial stack 510 of n-type and p-type semiconductors (e.g., GaN,InGaN, AlInGaP, GaAs, InGaAs). The thickness of the epitaxial stack 510may range from about 3 μm to about 15 μm, typically about 5 μm. Then-type semiconductor and p-type semiconductor of the epitaxial stack 510may make electrical contact to traces 514 on a substrate 516 via ann-contact 512 a and a p-contact 512 b, respectively. The n-contact 512 aand p-contact 512 b (or interconnect material) may be formed from ametal or compound such as Au, Sn, AuSn, In, Anisotropic conductive film(ACF)/ACInk, Self-Aligned Contact (SAC). The thickness of the contact512 a and p-contact 512 b may range from about 0.02 μm to about 5 μm,typically about 0.1 μm. The traces 514 may be formed from a TCOmaterial. The thickness of the traces 514 may range from about 0.5 μm toabout 10 μm, typically about 1 μm. The n-contact 512 a and p-contact 512b may be patterned and formed from a metal, such as copper (Cu), nickel(Ni), gold (Au), silver (Ag), and/or titanium (Ti), for example, whichmay be deposited on the epitaxial stack 510. The substrate 516 may bethe rigid or flexible substrate described above formed, for example,from glass, PET, polyamideimide, polyetherimide, or clear polyimide. Thethickness of the substrate 516 may range from about 50 μm to about 1000μm, typically about 100 μm. Metallic conductors 518 may make contact tothe traces 514 to route power and other signals to the epitaxial stack510. The metallic conductors 518 may be formed from a metal or compoundsuch as Au, Cu, Al, Ti, Ni, or Mo. The thickness of the metallicconductors 518 may range from about 0.5 μm to about 30 μm, typicallyabout 1 μm.

In some embodiments, a light-converting layer 520 containing phosphorparticles may be disposed on or adjacent to the epitaxial stack 510. Thelight-converting layer 520 may convert the light emitted by theepitaxial stack 510 to white light, for example.

A lens 530 and/or other optical elements may be disposed over theepitaxial stack 510 as shown. The lens 530 and/or other optical elementsmay be incorporated in the adhesive layer. Although not shown, the othersubstrate may be disposed on the lens 530.

FIG. 5B illustrates a cross-sectional view of an LED 500 b of anothersparse array, in accordance with some examples. As indicated, thedifference between the LED 500 b of FIG. 5B and the LED 500 a of FIG. 5Ais the presence of a submount 522 (the optional light-converting layer520 and lens 530 are not shown in FIG. 5B for convenience). The submount522 may be a rigid substrate formed, for example, from glass or silicon.The thickness of the submount 522 may range from about 5 μm to about 100μm, typically about 20 μm. The interconnect material may be the same onboth sides of the submount 522.

In some embodiments, vertical singulated LEDs may have a smallest x-ydimensions of about 3 μm×about 3 μm and a largest x-y dimensions ofabout 15 μm×about 15 μm. Lateral and flip chip LEDs may have a smallestx-y dimensions of about 3 μm×about 6 μm and a largest x-y dimensions ofabout 50 μm×about 75 μm in various embodiments. In this case, a 127μm×127 μm panel having a 200 pixels per inch (PPI) with a 40×40 μmmicroIC, 25×25 μm LED submount, 2×10 μm×127 μm traces to supply themicroIC, 2×10 μm×<50 μm traces to supply LEDs, the total opaque orsemi-opaque area of a tile is 5765 μm², the total area per pixel in 200ppi is 16129 μm², and the fractional area is 35% covered, 65%transparent. Similarly, a 362 μm×362 μm panel having a 70 pixels perinch (PPI) with a 40×40 μm microIC, 25×25 μm LED submount, 2×10 μm×362μm traces to supply the microIC, 2×10 μm×<150 μm traces to supply LEDs,the total opaque or semi-opaque area of the tile is 12465 μm², the totalarea per pixel in 70 ppi is 131044 μm², and the fractional area is 10%covered, 90% transparent. Either of these may provide panels withsufficient transparency to see through the panel. That is, in a sparsedisplay, a distance between LEDs of the sparse array of LEDs permitsdisplay of at least one of alphanumeric and image information whileproviding visibility through the transparent material.

As above, displays have always had a viewing side that emits light and aside that is full of electronics and components that operate to createthe light and images. Transparent displays enabled by microLEDs may havean emitting side and a backplane side. In some applications, it may bedesirable to emit light from one side of the display and emit no lightfrom a reverse side; in other applications, however, such a limitationmay be impractical and true light leakage prevention be solved by meansother than inherent design. In the current embodiments described herein,the surfaces ideal for transparent display integration may have utilityoutside in and inside out, and in many use cases, these are exclusive.Therefore, a display that can provide images of similar quality fromboth sides can greatly enhance the utility of the display whileefficiently using their size and integration effort.

FIG. 5C illustrates a cross-sectional view of an LED of another sparsearray, in accordance with some examples. The flip chip or lateral LED500 c of FIG. 5C may be a microLED that emits substantially equivalentlyfrom both sides, meaning that there are transparent contacts and regionsof both the n and p side of the structure to make electrical contactwith the n and p side of the structure. As shown in FIG. 5C, the LED 500c may contain a p-type semiconductor 532 a and an n-type semiconductor532 b on opposing sides of an active region 532 c that may includemultiple quantum well structure. A transparent contact 534 a may bedisposed on the p-type semiconductor 532 a. Similarly, a transparentprotective coating 536 or pattern that mimics the transparent contact534 a may be formed on the n-type semiconductor 532 b. The p-typesemiconductor 532 a and the active region 532 c may be etched to exposea portion of the n-type semiconductor 532 b. A transparent (ornon-transparent) contact 534 b may be formed on the exposed portion ofthe n-type semiconductor 532 b. Thus, the display backplane may besubstantially transparent, including the main emission area and amajority of electrical conduction traces connecting to the emissionarea. Examples of candidate materials include glass, PET,polyamideimide, polyetherimide, or clear polyimide for the substrate andITO or ZnO for the electrically conducting traces. The transparentcontacts may be, for example, very thin metals such as Ni at 50-80Angstroms thickness. Other thin metals may also be used, such as Al, Ti,Au, Ag, Mo for example. An interconnect or bonding system for the LED tothe backplane that is substantially transparent and has well controlledtransmission may also be used.

Note that it may be desirable for the transmission % between the top andbottom of the LED to be roughly equivalent, regardless of the dietype—as described vertical or lateral/flip chip. In the case of a flipchip LED, a broad contact (e.g., ITO/Ag) may be used on the mesa for thep contact, and, as the opposing side of the device may usually have nocontact and thus no metal on that surface, a layer (the transparentprotective coating 536 or pattern) may be used to make the transmissionequivalent to the contacted surface. The transparent protective coating536 or pattern may be similar to the actual contacting metals but mayalso be different (e.g., a metal or an oxide or a combination of the twomay be used).

FIG. 5D illustrates a cross-sectional view of an LED of another sparsearray, in accordance with some examples. The vertical LED 500 d of FIG.5D contains a p-type semiconductor 542 a and an n-type semiconductor 542b on opposing sides of an active region 542 c that may include multiplequantum well structure. A transparent contact 544 a, 544 b may berespectively disposed on the p-type semiconductor 542 a and the n-typesemiconductor 542 b. As the active regions 532 c, 542 c of FIGS. 5C and5D emit in all directions, light may be emitted from both thetransparent contact and, if present, the coating in the structures ofFIGS. 5C and 5D.

Although not shown, FIGS. 5C and 5D, other layers may be present, suchas depositing or otherwise forming a reflective material on thesidewalls of the semiconductor structures to limit light emitted fromthe active region being emitted from an edge of the semiconductorstructures. That is, substantially the entirety of the light emittedfrom the active region is emitted from a surface of the semiconductorstructures in a growth direction of the semiconductor structures (i.e.,in a direction between the transparent contacts). The reflectivematerial may be formed from one or more metal layers (e.g., Cu), or amultilayer Bragg reflector structure containing, e.g., layers of oxideof different refractive indices.

FIG. 6 shows a top view of an example panel 600. The panel 600 containsmultiple adjacent (touching) tiles 602 a, 602 b. Each tile 602 a, 602 bcontains an LED array 610. Each LED array 610 contains multiple LEDs 612arranged in a sparse distribution, similar to that described above. EachLED 612 may emit light of the same color or may emit different light ofdifferent colors. The electrical connections between the LEDs 612 andfrom LEDs 612 to other (external) components such as a driver are notshown for convenience. Multiple LEDs 612 of different colors may bearranged at each individual (pixel) location of the LEDs 612.

As shown, the panel 600 may be formed from adjacent LED arrays 610(tiles 602 a, 602 b). In some embodiments, each LED array 610 may be ofthe same size and may have the same number of LEDs 612. The LEDs 612within each LED array 610 may be separated by a uniform distance, orsubstantially uniform distance, D in both orthogonal (x-y) directions.Each LED 612 closest to the edge in each LED array 610 is disposed isdisposed at half the uniform distance D/2 from the edge of the LED array610.

Although the LEDs 612 are shown in FIG. 6 as being disposed in a squareLED array 610 (i.e., the number of LEDs 612 are the same in eachorthogonal direction) any shaped LED array (e.g., rectangular,triangular) may be used in the panel 600 so long as the LED arrays areable to fit together to be in contact on all sides with another LEDarray and the spacing between the LEDs 612 remains constant. Drivers andother control circuitry may be disposed at one electronics edge 620 oropposing edges of each tile 602 a, 602 b. The electronics edge 620 maybe orthogonal to a common edge between the tiles 602 a, 602 b. Theelectronics edge 620 may contain multiple drivers that are eachconfigured to drive one or more microLEDs in each pixel.

Thus, a display formed by the panel 600 may essentially be edgeless.That is, at most three sides may be free from any visible powerconductors or signal busses. Such a display may be formed from multipletiles 602 a, 602 b having essentially identical characteristics andsubstantially uniform distance between pixels (LEDs) to form a largerdisplay.

Although not shown, in some embodiments every panel or tile may containone or more control components. The control components may include oneor more sensors to detect users in proximity of the panel and/or tileand provide feedback to the processor. In addition, the panel or tilemay include other sensors, such as touch sensors, to allow the panel ortile to be used as a user input device in addition to merely displayinginformation. In this case, the panel or tile may, for example, displayan alphanumeric pad using the panel or tile on a side window thatcontains the sparse LED array (which display may be initiated based on aproximity sensor in the panel detecting the presence of a user). Thepanel or tile may also include one or more connectors to externaldigital signals, conductors and interfaces for power supply to the panelor tile, as well as other control circuitry. Integrated circuits thatsupply current to LEDs for one or more pixels may be included for everynth pixel. In addition, every pixel may include multiple LEDs ofdifferent colors (e.g., red, green, and blue LEDs), in addition toconductors for power and digital signals to enable delivery of apredetermined current to the LEDs.

FIG. 7 illustrates an example of a panel with a single tile. The panel700 may include a single tile that has a sparse LED array 702, anelectronics edge 704, and a connector 706 electrically coupled to theelectronics edge 704. The various components are described above. In anoff mode, the panel 700 is transparent. The panel 700 may providedisplay on a single side or on opposite sides, as described herein.

FIGS. 8A-8B illustrate an example of a panel with multiple displaytiles. Similar to FIG. 7 , each tile of the panel 800 a, 800 b in FIGS.8A and 8B may include a sparse LED array 802, an electronics edge 804,and a connector 806 electrically coupled to the electronics edge 804.For the rectangular tiles shown in FIGS. 8A-8B, in FIG. 8A theelectronics edge 804 of the panel 800 a may be disposed along a singlecontinuous edge that forms the long edge of each tile of the panel 800 a(with the short edge being common between the rectangular tiles); inFIG. 8B the electronics edge 804 of the panel 800 b may be disposedalong opposing edges that form the short edges of each tile of the panel800 b (with the long edge being common between the rectangular tiles).In an off mode, the panel 800 b is transparent. The panel 800 b mayprovide display on a single side or on opposite sides. In FIGS. 8A and8B the tiles are the same size; in other embodiments the tiles may bedifferent sizes, so long as the distance between pixels (that containmultiple different color LEDs) is the same.

FIGS. 9A and 9B show examples of a sparse LED array arrangement. Asdescribed herein, the dual-sided panel 900 a, 900 b (e.g., a dual-sideddisplay) may contain a panel 914 that contains multiple sparse LEDarrays 912 a, 912 b disposed back-to-back. The individual (or sets ofpixels) of the sparse LED arrays 912 a, 912 b. Each of the sparse LEDarrays 912 a, 912 b may be disposed on a non-transparent substrate,thereby limiting viewing of the information projected to only onehemisphere. A connection 918, such as a cable or wiring, may providepower and enable control by a processor of the panel 914 via traces 916connected to electronics of the panel 914 that control the sparse LEDarrays 912 a, 912 b. As shown in FIG. 9A, the panel 914 may be disposedwithin a cavity formed by the transparent material 910. An end of thepower connection 918 may be retained within the transparent material 910to provide a robust electrical connection with the traces 916. As shownin FIG. 9B, the panel 914 may instead be disposed on the transparentmaterial 910 and protected by a protective layer 920, such as PET. Theuse of a dual-sided sparse LED array arrangement as described in FIGS.9A and 9B may permit different information to be displayed to observerson opposite sides of the transparent material 910 without limitingviewing through the transparent material 910 in either direction.

FIG. 10 shows an example display. The display 1000 may include a displaystack 1002 that includes, for example, the LEDs shown in FIG. 5C or 5Din the sparse array in the panel shown in FIG. 6 . The display stack1002 may thus include LEDs (such as microLEDs) that emit substantiallyequivalently from both sides of the display 1000, as provided by thetransparent contacts and regions of both the n and p side of thestructure in FIG. 5C or 5D. In addition, the backplane of the display1000 (not shown in FIG. 10 ) may be substantially transparent, includingthe main area of emission (the area of the LED array) and a majority ofelectrically conductive traces that provide power and control to theLEDs of the array (and other components of the panel). The substrate maythus be formed from one or more materials such as glass, PET,polyamideimide, polyetherimide, or clear polyimide and the electricallyconducting traces may be formed from one or more TCO materials such asITO. An interconnect or bonding system for the LEDs to the backplane mayalso be substantially transparent.

In some embodiments, the display stack 1002 may include the LEDs,backplane (traces, power inputs, substrate) controls/processors etc. Insome embodiments, the display stack 1002 may have a frontside on whichthe microLEDs are disposed and a backside forming the backplane. In someembodiments, the display stack 1002 may include the LEDs, backplane(traces, power inputs, substrate) controls/processors etc. In someembodiments, the display stack 1002 may have a frontside on which themicroLEDs are disposed and a backside forming the backplane.

A darkening layer 1004 a, 1004 b may be disposed on the outermost sideof each side of the display stack 1002. The darkening layer 1004 a, 1004b may have various support structures; in some embodiments, thedarkening layer 1004 a, 1004 b may be disposed on the substantiallytransparent contacts (or on a transparent support layer), while in otherembodiments, the darkening layer 1004 a, 1004 b may be separate from thepanel as a separate layer on the display 1000 (and thus have a separatesupport structure). The darkening layer 1004 a, 1004 b may be selectableto darken (thereby providing selectable darkening) such that light isonly emitted from one side of the display 1000. The darkening layer 1004a, 1004 b may be formed from, or may include, an electro-chromicmaterial (thereby providing an electro-chromic structure in thedisclosed subject-matter) that changes opacity in response to anelectrical signal, thereby being able to provide, for example,electro-chromatic darkening. The electro-chromic material may alsoinclude a liquid crystal display (LCD), in which polarization of theliquid crystal in the cells is changed by 90° to block light (which maybe polarized by a polarization film on the LED and/or on the side of thedarkening layer 1004 a, 1004 b opposing the display stack 1002) from thedisplay stack 1002. The activation of the darkening layer 1004 a, 1004 bon one side of the display 1000 may provide improved contrast forviewing light from the display stack 1002 on the opposite side of thedisplay 1000 by blocking the light generated by the LEDs in the displaystack 1002 from exiting the dual-sided display on one side of thedisplay 1000 (or the panel forming the display stack 1002). In someembodiments, rather than using an electro-chromic material, an iris orother mechanically-activated layer may be used to provide the darkeninglayer 1004 a, 1004 b.

The darkening layer 1004 a, 1004 b may have a transparent mode in whichthe darkening layer 1004 a, 1004 b is transparent and thus light fromthe display stack 1002 is transmitted and an opaque mode in which thedarkening layer 1004 a, 1004 b is opaque and thus light from the displaystack 1002 is blocked. The darkening layer 1004 a, 1004 b may bedisposed on only one side of the display stack 1002 or on both sides ofthe display stack 1002. Each darkening layer 1004 a, 1004 b may beindependently activatable such that none, one, or both darkening layers1004 a, 1004 b may be activated (opaque) or deactivated (transparent).The darkening layer 1004 a, 1004 b may be controlled by a processor. Theprocessor may be part of the panel or display 1000 or may be within thesystem of which the display 1000 is a part. In some embodiments, theentire area of the darkening layer 1004 a, 1004 b may be controlled bythe processor as a single element, i.e., the entire darkening layer 1004a, 1004 b may have the same state (transparent, opaque, or anintermediate state). In other embodiments, the darkening layer 1004 a,1004 b may be segregated into multiple regions and the regionsindividually controlled by the processor.

In some embodiments, the darkening layer 1004 a, 1004 b may becontrolled in response to sensor information. One or more sensors mayprovide the sensor information to the processor. Like the darkeninglayer 1004 a, 1004 b, the sensors may be integrated into the panel ordisplay 1000 or may be within the system of which the display 1000 is apart.

The sensors may include a proximity sensor and/or a (capacitive) touchsensor. The proximity sensor and touch sensor may respectively enablepresence detection and use detection to provide user experience. Theproximity sensor may sense which side of the display 1000 that a user ison and correctly orient the display image. The proximity sensor may useinfrared light to determine the presence of a user on one side of thedisplay 1000. The processor may determine the user presence for apredetermined amount of time (e.g., greater than about 5 seconds) andactive the darkening layer 1004 a, 1004 b on the other side of thedisplay 1000 as the user. Alternatively, the proximity sensor mayinclude a camera and the processor may determine the user presence fromfacial recognition of images captured by the camera.

In general, each pixel in display 1000 may emit light in a directionsymmetric around a normal direction that is normal to the underlyingportion on which the pixel is disposed. In some embodiments, the lightfrom each pixel may radiate in a Lambertian pattern, for example.However, propagation of the light in the normal direction may result ina diminished viewing capacity for individuals not within the main lobeof the Lambertian pattern as a significant portion of the light isdirected towards a direction that is not viewable. To this end, in someembodiments, one or more optical elements in the sparse array may beused to adjust the emission angle to an optimized direction in which the(Lambertian) pattern of the emitted light centers around a primarynon-normal viewing angle for a viewing position based on the detecteduser location. Eye tracking information may also be used to adjust thelight emission angle similar to augmented reality/virtual realitysystems.

Alternatively, rather than the LEDs shown in FIG. 5C or 5D being used,in other embodiments, the dual-sided arrays shown in FIG. 9A or 9B maybe used in the embodiment shown in FIG. 10 . In this case, as the arraysmay be independently controlled, and thus able to show the sameinformation or different information, the darkening layer 1004 a, 1004 bmay or may not be present.

FIG. 11 shows an example system. The system 1100 may include one or morelight sources 1110 a, 1110 b. A first light source 1110 a may includeone or more of the sparse LED arrays 1112 as described herein. The firstlight source 1110 a may include local drivers 1114, as also describedherein. The first light source 1110 a may be disposed in variouslocations on or within an apparatus, as described in more detail herein.A second light source 1110 b may be present and may include one or morenon-sparse LED arrays 1116 (e.g., microLED arrays, miniLEDs arrays, orother). The second light source 1110 b may be disposed in various otherlocations on or within an apparatus containing the system 1100.

The LEDs in the first light source 1110 a and/or second light source1110 b may contain microLEDs. A microLED array contains thousands tomillions of microscopic microLEDs that emit light and that may beindividually controlled or controlled in groups of pixels (e.g., 5×5groups of pixels). The microLEDs are small (e.g., <0.07 mm on a side)and may provide monochromatic or multi-chromatic light, typically red,green, blue, or yellow using inorganic semiconductor material such asthat indicated above. Other LEDs may have a size, for example, of about4 mm², 250 micron×250 micron, or larger. MicroLEDs may be used due totheir thickness about a 5 μm thickness or so, similar to thin film LEDs,and, as there is no substrate inherent to microLEDs, microLEDs may beable to be placed directly on a backplane. This results in a lightsource that has an overall thickness that is substantially less thanthat using other LEDs and permits the use of the MicroLEDs in thestructures described herein. The individual control provided by themicroLEDs allows the driving electronics for displays to use either anactive matrix array of driving transistors or a full driver microICsindividual intensity control. The use of microICs may be used to bring asubstantial amount of fine control to each LED operation.

A controller 1130 may include a processor 1132, which may be used tocontrol various functions of the system 1100. As also shown, thecontroller 1130 may contain further components, such as a driver 1134configured to drive, among others, the second light source 1110 b ascontrolled by the processor 1132. In some embodiments, the driver 1134may also be configured to provide non-local driving of the sparse LEDarrays 1112 of the first light source 1110 a.

As above, LEDs of the sparse LED arrays 1112 and non-sparse LED arrays1116 may be formed from one or more inorganic materials (e.g., binarycompounds such as gallium arsenide (GaAs), ternary compounds such asaluminum gallium arsenide (AlGaAs), quaternary compounds such as indiumgallium phosphide (InGaAsP), gallium nitride (GaN), or other suitablematerials), usually either III-V materials (defined by columns of thePeriodic Table) or II-VI materials. The LEDs in the different arrays mayemit light in the visible spectrum (about 400 nm to about 800 nm) and/ormay emit light in the infrared spectrum (above about 800 nm). At leastsome of the LEDs may be formed by combining n- and p-type semiconductorson a rigid substrate (which may be textured), for example, of sapphirealuminum oxide (Al2O3) or silicon carbide (SiC), among others. Inparticular, various layers are deposited and processed on the substrateduring fabrication of the LEDs. The surface of the substrate may bepretreated to anneal, etch, polish, etc. the surface prior to depositionof the various layers. The original substrate may be removed andreplaced by a thin transparent rigid substrate, such as glass, or aflexible substrate, for example plastic.

In general, the various LED layers may be fabricated using epitaxialsemiconductor deposition (e.g., by metal organic chemical vapordeposition) to deposit one or more semiconductor layers, metaldeposition (e.g., by sputtering), oxide growth, as well as etching,liftoff, and cleaning, among other operations. The substrate may beremoved from the LED structure after fabrication and after connection tocontacts on a backplane via metal bonding such as via wire or ballbonding. The backplane may be a printed circuit board or wafercontaining integrated circuits (ICs), such as a complementarymetal-oxide semiconductor (CMOS) IC wafer. The semiconductor depositionoperations may be used to create an LED with an active region in whichelectron-hole recombination occurs and the light from the LED isgenerated. The active region may be, for example, one or more quantumwells. Metal contacts may be used to drive provide current to the n- andp-type semiconductors from the ICs (such as drivers) of the backplane onwhich the LED is disposed. Methods of depositing materials, layers, andthin films may include, for example: sputter deposition, atomic layerdeposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), plasma enhanced atomic layer deposition (PEALD),plasma enhanced chemical vapor deposition (PECVD), and combinationsthereof, among others.

In some embodiments, one or more other layers, such as aphosphor-converting layer that contains phosphor particles, may bedisposed on some or all of the LEDs or some or all of the LED arrays1112, 1116 to convert at least a portion of the light from the LEDs tolight of a different wavelength. For example, blue light from GaN LEDsmay be converted into near infrared light or white light by thephosphor-converting layer.

The light sources 1110 a, 1110 b may include at least one lens and/orother optical elements such as reflectors. In different embodiments, asingle lens may be disposed over one or more of the LED arrays 1112,1116, multiple lenses may be disposed over one or more of the LED arrays1112, 1116 with a single lens disposed over one or more of the LEDarrays 1112, 1116, or multiple lenses may be disposed over one or moreof the LED arrays 1112, 1116 with a single lens disposed over one ormore of the LEDs of each of the LED arrays 1112, 1116. The at least onelens and/or other optical elements may direct the light emitted by theone or more of the LED arrays 1112, 1116 toward a target.

The processor 1132 may also control a sensor 1120 that includes amulti-pixel detector 1122. The sensor 1120 may sense light at thewavelength or wavelengths emitted by the second LED array 1116 andreflected by a target and/or radiation that is emitted by the target.The sensor 1120 may, for example, be a radar or lidar sensor, or theprocessor 1132 may be used to determine the presence of specific objects(e.g., other vehicles, people, road signs) nearby. The sensor 1120 mayinclude optical elements (e.g., at least one sensor lens) to capture theradiation. The multi-pixel detector 1122 may include, for example,photodiodes or one or more other detectors capable of detecting light inthe wavelength range(s) of interest.

The multi-pixel detector 1122 may include multiple different arrays tosense visible and/or infrared light. The multi-pixel detector 1122 mayhave one or more segments (that are able to sense the samewavelength/range of wavelengths or different wavelength/range ofwavelengths), similar to the LED array 1116.

In some embodiments, instead of, or in addition to, being provided inthe sensor 1120, a multi-pixel detector may be provided in the secondlight source 1110 b. In some embodiments, the second light source 1110 band the sensor 1120 may be integrated in a single module, while in otherembodiments, the second light source 1110 b and the sensor 1120 may beseparate modules that are disposed on a printed circuit board (PCB) orother mount. In other embodiments, the second light source 1110 b andthe sensor 1120 may be attached to different PCBs or mounts.

The LEDs in each of the LED arrays 1112, 1116 may be driven in an analogor digital manner, i.e., using a direct current (DC) driver or pulsewidth modulation (PWM). As shown, drivers 1114, 1134 may be used torespectively drive the LEDs in the LED array 1112, 1116, as well asother components, such as the actuators.

The components of the system 1100 shown in FIG. 10 may be provided powerusing a power supply 1140, such as a battery.

The first light source 1110 a may be arranged to emit light in sparsedistribution such that the LEDs occupy a small areal density so as toenable visual observation of information provided by the first lightsource 1110 a while permitting viewing through the underlyingtransparent (flexible) substrate of the regions between the LEDs along aline of sight that passes through the regions between the LEDs. This mayallow an observer on the emitting side of the first light source 1110 ato view the information projected by first light source 1110 a as wellas the underlying scene. In other embodiments in which the underlyingsubstrate is fully reflective to visible light or specularly reflective,the regions between the LEDs may not be viewable.

The information projected by first light source 1110 a may be static ormoving, similar to that able to be formed from a non-sparse lightsource. The LEDs of the first light source 1110 a may be electricallyconnected using conductive traces on the substrate that are configuredto provide drive current to the LEDs from the drivers 1114. As above,the conductive traces may be transparent and include one or more layersof TCO. The conductive traces, even if formed from a non-transparentmetal, may be relatively narrow and spaced sufficiently far apart topermit visual observation through the substrate without substantialinterference. The conductive traces may, for example, be less than about110 μm wide. The LEDs may be connected in series or parallel via theconductive traces along each of a row and column to the edge or edgescontaining the control circuitry (and power supply) and may be addressedindividually or in groups of LEDs. The drivers 1114 and other controldevices in the first light source 1110 a for each pixel may also bereferred to as a microIC.

FIG. 12 illustrates an example of a general device in accordance withsome embodiments. The device 1200 may be a vehicle-embedded display forexample. Various elements may be provided on a backplane indicatedabove, while other elements may be local or remote. Examples, asdescribed herein, may include, or may operate on, logic or a number ofcomponents, modules, or mechanisms.

Modules and components are tangible entities (e.g., hardware) capable ofperforming specified operations and may be configured or arranged in acertain manner. In an example, circuits may be arranged (e.g.,internally or with respect to external entities such as other circuits)in a specified manner as a module. In an example, the whole or part ofone or more computer systems (e.g., a standalone, client or servercomputer system) or one or more hardware processors may be configured byfirmware or software (e.g., instructions, an application portion, or anapplication) as a module that operates to perform specified operations.In an example, the software may reside on a machine readable medium. Inan example, the software, when executed by the underlying hardware ofthe module, causes the hardware to perform the specified operations.

Accordingly, the term “module” (and “component”) is understood toencompass a tangible entity, be that an entity that is physicallyconstructed, specifically configured (e.g., hardwired), or temporarily(e.g., transitorily) configured (e.g., programmed) to operate in aspecified manner or to perform part or all of any operation describedherein. Considering examples in which modules are temporarilyconfigured, each of the modules need not be instantiated at any onemoment in time. For example, where the modules comprise ageneral-purpose hardware processor configured using software, thegeneral-purpose hardware processor may be configured as respectivedifferent modules at different times. Software may accordingly configurea hardware processor, for example, to constitute a particular module atone instance of time and to constitute a different module at a differentinstance of time.

The electronic device 1200 may include a hardware processor (orequivalently processing circuitry) 1202 (e.g., a central processing unit(CPU), a GPU, a hardware processor core, or any combination thereof), amemory 1204 (which may include main and static memory), some or all ofwhich may communicate with each other via an interlink (e.g., bus) 1208.The memory 1204 may contain any or all of removable storage andnon-removable storage, volatile memory or non-volatile memory. Theelectronic device 1200 may further include a display/light source 1210such as the LEDs described above, or a video display, an alphanumericinput device 1212 (e.g., a keyboard), and a user interface (UI)navigation device 1214 (e.g., a mouse). In an example, the display/lightsource 1210, input device 1212 and UI navigation device 1214 may be atouch screen display. The electronic device 1200 may additionallyinclude a storage device (e.g., drive unit) 1216, a signal generationdevice 1218 (e.g., a speaker), a network interface device 1220, one ormore cameras 1228, and one or more sensors 1230, such as a globalpositioning system (GPS) sensor, compass, accelerometer, or other sensorsuch as those described herein. The electronic device 1200 may furtherinclude an output controller, such as a serial (e.g., universal serialbus (USB), parallel, or other wired or wireless (e.g., infrared (IR),near field communication (NFC), etc.) connection to communicate orcontrol one or more peripheral devices (e.g., a printer, card reader,etc.). Some of the elements, such as one or more of the sparse arraysthat provide the display/light source 1210 may be remote from otherelements and may be controlled by the hardware processor 1202.

The storage device 1216 may include a non-transitory machine readablemedium 1222 (hereinafter simply referred to as machine readable medium)on which is stored one or more sets of data structures or instructions1224 (e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 1224 may alsoreside, completely or at least partially, within the memory 1204 and/orwithin the hardware processor 1202 during execution thereof by theelectronic device 1200. While the machine readable medium 1222 isillustrated as a single medium, the term “machine readable medium” mayinclude a single medium or multiple media (e.g., a centralized ordistributed database, and/or associated caches and servers) configuredto store the one or more instructions 1224.

The term “machine readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe electronic device 1200 and that cause the electronic device 1200 toperform any one or more of the techniques of the present disclosure, orthat is capable of storing, encoding or carrying data structures used byor associated with such instructions. Non-limiting machine-readablemedium examples may include solid-state memories, and optical andmagnetic media. Specific examples of machine-readable media may include:non-volatile memory, such as semiconductor memory devices (e.g.,Electrically Programmable Read-Only Memory (EPROM), ElectricallyErasable Programmable Read-Only Memory (EEPROM)) and flash memorydevices; magnetic disks, such as internal hard disks and removabledisks; magneto-optical disks; Random Access Memory (RAM); and CD-ROM andDVD-ROM disks.

The instructions 1224 may further be transmitted or received over acommunications network using a transmission medium 1226 via the networkinterface device 1220 utilizing any one of a number of wireless localarea network (WLAN) transfer protocols or a SPI or CAN bus. Examplecommunication networks may include a local area network (LAN), a widearea network (WAN), a packet data network (e.g., the Internet), mobiletelephone networks (e.g., cellular networks), Plain Old Telephone (POTS)networks, and wireless data networks. Communications over the networksmay include one or more different protocols, such as Institute ofElectrical and Electronics Engineers (IEEE) 802.11 family of standardsknown as Wi-Fi, IEEE 802.14 family of standards known as WiMax, IEEE802.14.4 family of standards, a Long Term Evolution (LTE) family ofstandards, a Universal Mobile Telecommunications System (UMTS) family ofstandards, peer-to-peer (P2P) networks, a next generation (NG)/6^(th)generation (6G) standards among others. In an example, the networkinterface device 1220 may include one or more physical jacks (e.g.,Ethernet, coaxial, or phone jacks) or one or more antennas to connect tothe transmission medium 1226.

Note that the term “circuitry” as used herein refers to, is part of, orincludes hardware components such as an electronic circuit, a logiccircuit, a processor (shared, dedicated, or group) and/or memory(shared, dedicated, or group), an Application Specific IntegratedCircuit (ASIC), a field-programmable device (FPD) (e.g., afield-programmable gate array (FPGA), a programmable logic device (PLD),a complex PLD (CPLD), a high-capacity PLD (HCPLD), a structured ASIC, ora programmable SoC), digital signal processors (DSPs), etc., that areconfigured to provide the described functionality. In some embodiments,the circuitry may execute one or more software or firmware programs toprovide at least some of the described functionality. The term“circuitry” may also refer to a combination of one or more hardwareelements (or a combination of circuits used in an electrical orelectronic system) with the program code used to carry out thefunctionality of that program code. In these embodiments, thecombination of hardware elements and program code may be referred to asa particular type of circuitry.

The term “processor circuitry” or “processor” as used herein thus refersto, is part of, or includes circuitry capable of sequentially andautomatically carrying out a sequence of arithmetic or logicaloperations, or recording, storing, and/or transferring digital data. Theterm “processor circuitry” or “processor” may refer to one or moreapplication processors, one or more baseband processors, a physicalcentral processing unit (CPU), a single- or multi-core processor, and/orany other device capable of executing or otherwise operatingcomputer-executable instructions, such as program code, softwaremodules, and/or functional processes.

The camera 1228 may sense light at least the wavelength or wavelengthsemitted by the LEDs. The camera 1228 may include optical elements (e.g.,at least one camera lens) that are able to collect reflected light ofillumination that is reflected from and/or emitted by an illuminatedregion. The camera lens may direct the reflected light onto amulti-pixel sensor (also referred to as a light sensor) to form an imageof on the multi-pixel sensor.

The processor 1202 may control and drive the LEDs via one or moredrivers. For example, the processor 1202 may optionally control one ormore LEDs in LED arrays independent of another one or more LEDs in theLED arrays, so as to illuminate an area in a specified manner.

In addition, the sensors 1230 may be incorporated in the camera 1228and/or the light source 1210. The sensors 1230 may sense visible and/orinfrared light and may further sense the ambient light and/orvariations/flicker in the ambient light in addition to reception of thereflected light from the LEDs. The sensors may have one or more segments(that are able to sense the same wavelength/range of wavelengths ordifferent wavelength/range of wavelengths), similar to the LED arrays.

FIGS. 13A-13G illustrate an example of a process 1300 of fabricating thesparse array in accordance with some embodiments. FIG. 14 illustrates anexample of a method 1400 of fabricating the sparse array in accordancewith the process operations shown in FIGS. 13A-13G. With concurrentreference to FIGS. 13A-13G and FIG. 14 , the process starts in FIG. 13Awith a transparent flexible sheet 1302. At operation 1402 in FIG. 14 ,the transparent flexible sheet 1302 may be attached to a carrier wafer1304 (or other type of carrier substrate) as depicted in FIG. 13B. Atoperation 1404, metal traces 1306 may be deposited on the transparentflexible sheet 1302 as shown in FIG. 13C. At operation 1406, the LEDarray 1308 may be assembled on the metal traces 1306 as shown in FIG.13D. At operation 1408, the transparent flexible sheet 1302 containingthe metal traces 1306 and the LED array 1308 may be released from thecarrier wafer 1304 as shown in FIG. 13E. At operation 1410, an adhesivelayer 1310 may be laminated on the transparent flexible sheet 1302 tocover the metal traces 1306 and the LED array 1308 as shown in FIG. 13F.At operation 1412, the transparent flexible sheet 1302 may be flippedand laminated onto a printed circuit board 1312 as shown in FIG. 13G.

In other embodiments, a backplane with traces may be formed on thetransparent substrate. The sparse LED array (which may containmicroLEDs) may be transferred onto the transparent substrate with thebackplane. The transfer may be performed, for example, using a masstransfer process to provide the sparse LED array. The mass transfer maybe used to deposit the microLEDs (and microIC) mass on the transparentsubstrate by picking the location with stamps and tethering or anchoringthe transferred material using an adhesive layer, for example. Thetransfer may be performed, in another example, using one or more printnozzles arrayed in parallel to provide the sparse LED array in a vacuumnozzle transfer process. The print nozzles may be an ENJET tool adaptedfor this process. The laminated structure may then be formed in eithercase. In other embodiments, after transfer, specific microLEDs may berepaired or replaced using the ENJET Tool.

Alternatively, traces may be formed on the transparent substrate. TheLEDs may then be formed on the transparent substrate and the laminatedstructure formed as above.

FIG. 15 illustrates an example of a process of providing improvedcontrast in accordance with some embodiments. During the process 1500,the presence of a user on one side of the sparse display is determinedat operation 1502. The user presence may be detected using a proximitydetector, for example. At operation 1504, one of the darkening layersthat are disposed on both sides of the display is activated to darkenthat side of the display. Specifically, the darkening layer on theopposite side of the display as the detected user is activated toeliminate light being transmitted through the display from the oppositeside of the display as the detected user and improve the image contrastfor the user. In the various embodiments herein, the darkening layerrather than being an opaque layer when contrast is desired may insteadbe a mirror, controllable to reflect light from the LEDs back towardsthe direction of the user. In this case, optical elements at thedarkening layer may be used to adjust the reflected light to emulatelight from the LEDs emitted directly towards the user.

FIG. 16 shows an example display stack in accordance with variousembodiments of the disclosed subject-matter. The display stack 1600 mayinclude a number of layers such as those described above. As shown, thedarkening layer 1602 a, 1602 b may be the outermost layer of the displaystack 1600. The darkening layer 1602 a, 1602 b may include anelectro-chromatic material, LCD, or e-ink, among others. The thicknessof the darkening layer 1602 a, 1602 b may range from about 15 μm toabout 500 μm, typically about 50 μm. The darkening layer 1602 a, 1602 bmay be attached to a transparent substrate 1606 a, 1606 b using atransparent adhesive 1604 a, 1604 b. The transparent adhesive 1604 a,1604 b may include silicone, siloxane, epoxy-silicone hybrid, epoxy, oracrylic, among others. The thickness of the transparent adhesive 1604 a,1604 b may range from about 2 μm to about 100 μm, typically about 10 μm.The transparent substrate 1606 a, 1606 b may include Glass, PET, orClear PI, among others. The thickness of the transparent substrate 1606a, 1606 b may range from about 50 μm to about 1000 μm, typically about100 μm. One of the transparent substrates 1606 a, 1606 b may be a dummybackplane for mechanical support.

The microLED 1610 may be embedded in a conformal transparent adhesive1608. The conformal transparent adhesive 1608 may include silicone,siloxane, epoxy-silicone hybrid, epoxy, or acrylic, among others. Thethickness of the conformal transparent adhesive 1608 may range fromabout 10 μm to about 100 μm, typically about 25 μm. The microLED 1610may include GaN, InGaN, AlInGaP, GaAs, or InGaAs (i.e., light emittingsemiconductors). The thickness of the microLED 1610 may range from about3 μm to about 15 μm, typically about 5 μm.

The microLED 1610 may be attached to a transparent oxide conductor 1614via an interconnect metal 1612. The interconnect metal 1612 may includeAu, Sn, AuSn, In, ACF/ACInk, or SAC, among others. The thickness of theinterconnect metal 1612 may range from about 0.02 μm to about 5 μm,typically about 0.1 μm. The transparent oxide conductor 1614 may includeITO, ZnO, or SnO, among others. The thickness of the transparent oxideconductor 1614 may range from about 0.5 μm to about 10 μm, typicallyabout 1 μm.

The embodiments described herein may be used for video and signagedisplays that blend seamlessly in with transparent surfaces. Otherembodiments may include retail windows or glass informationinstallations, and automotive windows including windshields. Althoughsparse arrays are discussed in detail herein, in other embodiments theuse of microLEDs having the structure described in, for example, FIG. 5Cor 5D may be used in non-sparse arrays to provide similar displays asthose described above, e.g., as shown in FIG. 10 .

Note that in various embodiments in which a panel has multiple tiles,the electronics/controls (MicroIC control circuits on a thin transparentelectrical backplane) may be on the same side or may be on differentsides for a one sided display. The tiles of a panel may be able tooperate independently and may provide multiple unrelated images or maybe aggregated to operate as a control for a single display.

In some cases (e.g., extreme miniaturization), the backplane may beformed from silicon CMOS, making the availability of a two way displaymore limited. Like the disclosed two way display, however, even if thebackplane is formed from silicon CMOS, such a display may be used asdisplays in which systems such as in a laptop used as a laptop and atablet.

EXAMPLES

Example 1 is a dual-sided display, comprising a panel having at leastone tile configured to display information, the panel disposed within atransparent material, each of the at least one tile including an arrayof micro light-emitting diodes (microLEDs), the microLEDs configured toprovide light to be viewed on opposing sides of the panel, a distancebetween the microLEDs configured to provide visibility through thepanel.

In Example 2, the subject matter of Example 1 includes, wherein in eachtile of the panel, the array includes: a transparent flexible substrate;a transparent rigid substrate adhered to the transparent flexiblesubstrate via an adhesive layer in which the array is encapsulated; andat least one driver disposed on an edge of the tile and configured todrive the microLEDs.

In Example 3, the subject matter of Examples 1-2 includes, wherein eachLED includes: an n-type semiconductor layer; a p-type semiconductorlayer; an active region between the n-type semiconductor layer and thep-type semiconductor layer; and a transparent contact disposed on eachof the n-type semiconductor layer and the p-type semiconductor layer.

In Example 4, the subject matter of Examples 1-3 includes, wherein eachLED includes: an n-type semiconductor layer; a p-type semiconductorlayer; an active region between the n-type semiconductor layer and thep-type semiconductor layer; at least one material selected frommaterials including a transparent contact and a transparent coatingdisposed on each of the n-type semiconductor layer and the p-typesemiconductor layer; and a non-transparent contact disposed on a surfaceof one of the n-type semiconductor layer and the p-type semiconductorlayer opposite a surface of the one of the n-type semiconductor layerand the p-type semiconductor layer on which the transparent coating isdisposed, the non-transparent contact adjacent to the active region.

In Example 5, the subject matter of Examples 1-4 includes, a darkeninglayer disposed on at least one side of the panel, the darkening layerconfigured to provide selectable darkening to block the light fromexiting the dual-sided display on the at least one side of the panel.

In Example 6, the subject matter of Example 5 includes, wherein thedarkening layer includes an electro-chromatic structure configured toprovide electro-chromatic darkening.

In Example 7, the subject matter of Example 5 includes, wherein thedarkening layer includes a liquid crystal display (LCD).

In Example 8, the subject matter of Examples 5-7 includes, a proximitysensor configured to detect user presence on a side of the display; anda processor configured to control the darkening layer to provide theselectable darkening to an opposite side of the display as the side ofthe display at which the user presence is detected by the proximitysensor.

In Example 9, the subject matter of Example 8 includes, wherein theproximity sensor is integrated in the panel.

In Example 10, the subject matter of Examples 5-9 includes, a touchsensor configured to receive user input on a side of the display; and aprocessor configured to control the darkening layer to provide theselectable darkening to an opposite side of the display as the side ofthe display at which the user input is received by the touch sensor.

In Example 11, the subject matter of Example 10 includes, wherein thetouch sensor is integrated in the panel.

In Example 12, the subject matter of Examples 1-11 includes, a firstdarkening layer disposed on a first side of the panel, the firstdarkening layer configured to provide selectable darkening to blocklight from exiting the dual-sided display on the first side of thepanel; and a second darkening layer disposed on a second side of thepanel opposing the first side of the panel, the second darkening layerconfigured to provide selectable darkening to block light from exitingthe dual-sided display on the second side of the panel, the firstdarkening layer and the second darkening layer configured to beindependently activatable between a transparent mode and an opaque mode.

In Example 13, the subject matter of Examples 1-12 includes, a darkeninglayer disposed on at least one side of the panel, the darkening layerconfigured to provide selectable darkening to block the light fromexiting the dual-sided display on the at least one side of the panel,the darkening layer configured to improve a contrast for viewing thelight on a side of the dual-sided display that is not darkened by thedarkening layer.

In Example 14, the subject matter of Examples 1-13 includes, wherein:the panel has multiple tiles, control circuitry of each tile is disposedon a thin transparent electrical backplane of the tile, and the controlcircuitry of each tile is disposed on a single side of the display.

In Example 15, the subject matter of Examples 1-14 includes, wherein:the panel has multiple tiles, control circuitry of each tile is disposedon a thin transparent electrical backplane of the tile, and the controlcircuitry of at least one tile is disposed on a different side of thedisplay as the control circuitry of at least one other tile.

In Example 16, the subject matter of Examples 1-15 includes, wherein:the panel has multiple tiles, and the tiles are configured to operateindependently to selectively provide different images or aggregated toprovide an extended display.

In Example 17, the subject matter of Examples 1-16 includes, wherein abackplane of the panel is formed from a silicon complementarymetal-oxide semiconductor (CMOS).

Example 18 is an array comprising a plurality of micro light-emittingdiodes (microLEDs) configured to provide light to be viewed on opposingsides of the array, a distance between the microLEDs configured toprovide visibility through the array.

In Example 19, the subject matter of Example 18 includes, a transparentflexible substrate; and a transparent rigid substrate adhered to thetransparent flexible substrate via an adhesive layer in which the arrayis encapsulated, wherein each microLED includes: an n-type semiconductorlayer; a p-type semiconductor layer; an active region between the n-typesemiconductor layer and the p-type semiconductor layer; and atransparent contact disposed on each of the n-type semiconductor layerand the p-type semiconductor layer.

In Example 20, the subject matter of Examples 18-19 includes, atransparent flexible substrate; and a transparent rigid substrateadhered to the transparent flexible substrate via an adhesive layer inwhich the array is encapsulated, wherein each microLED includes: ann-type semiconductor layer; a p-type semiconductor layer; an activeregion between the n-type semiconductor layer and the p-typesemiconductor layer; at least one material selected from materialsincluding a transparent contact and a transparent coating disposed oneach of the n-type semiconductor layer and the p-type semiconductorlayer; and a non-transparent contact disposed on a surface of one of then-type semiconductor layer and the p-type semiconductor layer opposite asurface of the one of the n-type semiconductor layer and the p-typesemiconductor layer on which the transparent coating is disposed, thenon-transparent contact adjacent to the active region.

In Example 21, the subject matter of Examples 19-20 includes, whereinthe array is a sparse array and the distance between the microLEDs inthe array is substantially uniform.

Example 22 is a display panel configured to display information,comprising: a sparse array of micro light-emitting diodes (microLEDs)configured to provide light to be viewed on opposing sides of the panel;and a darkening layer disposed on each side of the array, each darkeninglayer configured to provide selectable darkening to block light fromexiting the panel and configured to be independently activatable betweena transparent mode and an opaque mode.

In Example 23, the subject matter of Example 22 includes, wherein thearray is disposed within a conformal transparent adhesive between atransparent backplane and a transparent substrate, the darkening layersdisposed on an opposite surface of the transparent backplane and atransparent substrate as the array.

Example 24 is a computer system comprising a dual-sided display and aprocessor configured to control the dual-sided display to provide light,the computer system comprising a panel having at least one tileconfigured to display information, the panel disposed within atransparent material, each of the at least one tile including a sparsearray of micro light-emitting diodes (microLEDs), the processorconfigured to control the microLEDs to provide light to be viewed onopposing sides of the panel.

In Example 25, the subject matter of Example 24 includes, wherein ineach tile of the panel, the array includes: a transparent flexiblesubstrate; a transparent rigid substrate adhered to the transparentflexible substrate via an adhesive layer in which the array isencapsulated; and at least one driver disposed on an edge of the tileand configured to drive the LEDs.

In Example 26, the subject matter of Examples 24-25 includes, whereinthe panel further comprises a darkening layer disposed on at least oneside of the panel, the processor configured to control the darkeninglayer to provide selectable darkening to block the light from exitingthe dual-sided display on the at least one side of the panel.

In Example 27, the subject matter of Example 26 includes, wherein thedarkening layer includes at least one of a material selected from agroup of materials that include an electro-chromatic material, liquidcrystal display (LCD), and e-ink.

In Example 28, the subject matter of Examples 26-27 includes, aproximity sensor configured to detect user presence on a side of thedisplay, the processor configured to control the darkening layer toprovide the selectable darkening to an opposite side of the display asthe side of the display at which the user presence is detected by theproximity sensor.

In Example 29, the subject matter of Example 28 includes, wherein theproximity sensor is integrated in the panel.

In Example 30, the subject matter of Examples 26-29 includes, a touchsensor configured to receive user input on a side of the display, theprocessor configured to control the darkening layer to provide theselectable darkening to an opposite side of the display as the side ofthe display at which the user input is received by the touch sensor.

In Example 31, the subject matter of Example 30 includes, wherein thetouch sensor is integrated in the panel.

In Example 32, the subject matter of Examples 24-31 includes, whereinthe panel further comprises: a first darkening layer disposed on a firstside of the panel, the first darkening layer configured to provideselectable darkening to block light from exiting the dual-sided displayon the first side of the panel; and a second darkening layer disposed ona second side of the panel opposing the first side of the panel, thesecond darkening layer configured to provide selectable darkening toblock light from exiting the dual-sided display on the second side ofthe panel, the first darkening layer and the second darkening layerconfigured to be independently activatable between a transparent modeand an opaque mode.

In Example 33, the subject matter of Examples 24-32 includes, whereinthe panel further comprises a darkening layer disposed on at least oneside of the panel, the processor configured to control the darkeninglayer to provide selectable darkening to block the light from exitingthe dual-sided display on the at least one side of the panel, thedarkening layer configured to improve a contrast for viewing the lighton a side of the dual-sided display that is not darkened by thedarkening layer.

In Example 34, the subject matter of Examples 24-33 includes, wherein:the panel has multiple tiles, control circuitry of each tile is disposedon a transparent electrical backplane of the tile, the control circuitryof each tile is disposed on a single side of the display.

In Example 35, the subject matter of Examples 24-34 includes, wherein:the panel has multiple tiles, control circuitry of each tile is disposedon a transparent electrical backplane of the tile, the control circuitryof at least one tile is disposed on a different side of the display asthe control circuitry of at least one other tile.

In Example 36, the subject matter of Examples 24-35 includes, wherein:the panel has multiple tiles, and the processor controls the tiles tooperate independently to provide unrelated images.

In Example 37, the subject matter of Examples 24-36 includes, wherein:the panel has multiple tiles, and the processor controls the tiles toprovide a single extended display.

In Example 38, the subject matter of Examples 24-37 includes, whereinthe panel further comprises a backplane formed from a siliconcomplementary metal-oxide semiconductor (CMOS).

Example 39 is a computer system comprising: a dual-sided displayconfigured to emit light from opposing sides of the display; and aprocessor configured to control the light from the dual-sided display,the dual-sided display having a panel, the panel including: a sparsearray of micro light-emitting diodes (microLEDs) configured to emit thelight, and a darkening layer disposed on each side of the array, eachdarkening layer configured to independently switch between beingtransparent to the light and opaque to the light, the processorconfigured to control the array and the darkening layers to displayinformation to be selectively viewed on the opposing sides of the panel.

In Example 40, the subject matter of Example 39 includes, wherein: thepanel further includes a conformal transparent adhesive, a transparentbackplane, and a transparent substrate, the array is disposed within theconformal transparent adhesive between the transparent backplane and thetransparent substrate, and the darkening layers are disposed on anopposite surface of the transparent backplane and a transparentsubstrate as the array.

In Example 41, the subject matter of Examples 39-40 includes, aproximity sensor configured to detect user presence on a side of thedisplay, the processor configured to control one of the darkening layersto switch from transparent to opaque in response to detection of theuser presence, the one of the darkening layers being on an opposite sideof the display as the side of the display at which the user presence isdetected.

In Example 42, the subject matter of Examples 39-41 includes, a touchsensor configured to receive user input on a side of the display, theprocessor configured to control one of the darkening layers to switchfrom transparent to opaque in response to reception of the user input,the one of the darkening layers being on an opposite side of the displayas the side of the display at which the user input is received.

Example 43 is a computer system comprising: a dual-sided displayconfigured to emit light from opposing sides of the display; and aprocessor configured to control the light from the dual-sided display,the dual-sided display having a panel, the panel including: an array oflight-emitting diodes (LEDs) configured to emit the light, and adarkening layer disposed on each side of the array, each darkening layerconfigured to independently switch between being transparent to thelight and opaque or reflective to the light, the processor configured tocontrol the array and the darkening layers to display information to beselectively viewed on the opposing sides of the panel.

In Example 44, the subject matter of Example 43 includes, wherein: thepanel has multiple tiles, and the processor controls the tiles tooperate independently to selectively provide unrelated images or asingle extended display.

Example 45 is at least one machine-readable medium includinginstructions that, when executed by processing circuitry, cause theprocessing circuitry to perform operations to implement of any ofExamples 1-44.

Example 46 is an apparatus comprising means to implement of any ofExamples 1-44.

Example 47 is a system to implement of any of Examples 1-44.

Example 48 is a method to implement of any of Examples 1-44.

In some embodiments, other components may be present, while in otherembodiments not all of the components may be present. As indicatedherein, although the term “a” is used herein, one or more of theassociated elements may be used in different embodiments. For example,the term “a processor” configured to carry out specific operationsincludes both a single processor configured to carry out all of theoperations as well as multiple processors individually configured tocarry out some or all of the operations (which may overlap) such thatthe combination of processors carry out all of the operations. Further,the term “includes” may be considered to be interpreted as “includes atleast” the elements that follow.

While only certain features of the system and method have beenillustrated and described herein, many modifications and changes willoccur to those skilled in the art. It is, therefore, to be understoodthat the appended claims are intended to cover all such modificationsand changes. Method operations can be performed substantiallysimultaneously or in a different order.

What is claimed is:
 1. A dual-sided display, comprising a panel havingat least one tile configured to display information, the panel disposedwithin a transparent material, each of the at least one tile includingan array of micro light-emitting diodes (microLEDs), the microLEDsconfigured to provide light to be viewed on opposing sides of the panel,a distance between the microLEDs configured to provide visibilitythrough the panel.
 2. The dual-sided display of claim 1, wherein in eachtile of the panel, the array includes: a transparent flexible substrate;a transparent rigid substrate adhered to the transparent flexiblesubstrate via an adhesive layer in which the array is encapsulated; andat least one driver disposed on an edge of the tile and configured todrive the microLEDs.
 3. The dual-sided display of claim 1, wherein eachLED includes: an n-type semiconductor layer; a p-type semiconductorlayer; an active region between the n-type semiconductor layer and thep-type semiconductor layer; and a transparent contact disposed on eachof the n-type semiconductor layer and the p-type semiconductor layer. 4.The dual-sided display of claim 1, wherein each LED includes: an n-typesemiconductor layer; a p-type semiconductor layer; an active regionbetween the n-type semiconductor layer and the p-type semiconductorlayer; at least one material selected from materials including atransparent contact and a transparent coating disposed on each of then-type semiconductor layer and the p-type semiconductor layer; and anon-transparent contact disposed on a surface of one of the n-typesemiconductor layer and the p-type semiconductor layer opposite asurface of the one of the n-type semiconductor layer and the p-typesemiconductor layer on which the transparent coating is disposed, thenon-transparent contact adjacent to the active region.
 5. The dual-sideddisplay of claim 1, further comprising a darkening layer disposed on atleast one side of the panel, the darkening layer configured to provideselectable darkening to block the light from exiting the dual-sideddisplay on the at least one side of the panel.
 6. The dual-sided displayof claim 5, wherein the darkening layer includes at least one of amaterial selected from a group of materials that include anelectro-chromatic material, liquid crystal display (LCD), and e-ink. 7.The dual-sided display of claim 5, further comprising: a proximitysensor configured to detect user presence on a side of the display; anda processor configured to control the darkening layer to provide theselectable darkening to an opposite side of the display as the side ofthe display at which the user presence is detected by the proximitysensor.
 8. The dual-sided display of claim 7, wherein the proximitysensor is integrated in the panel.
 9. The dual-sided display of claim 5,further comprising: a touch sensor configured to receive user input on aside of the display; and a processor configured to control the darkeninglayer to provide the selectable darkening to an opposite side of thedisplay as the side of the display at which the user input is receivedby the touch sensor.
 10. The dual-sided display of claim 9, wherein thetouch sensor is integrated in the panel.
 11. The dual-sided display ofclaim 1, further comprising: a first darkening layer disposed on a firstside of the panel, the first darkening layer configured to provideselectable darkening to block light from exiting the dual-sided displayon the first side of the panel; and a second darkening layer disposed ona second side of the panel opposing the first side of the panel, thesecond darkening layer configured to provide selectable darkening toblock light from exiting the dual-sided display on the second side ofthe panel, the first darkening layer and the second darkening layerconfigured to be independently activatable between a transparent modeand an opaque mode.
 12. The dual-sided display of claim 1, furthercomprising a darkening layer disposed on at least one side of the panel,the darkening layer configured to provide selectable darkening to blockthe light from exiting the dual-sided display on the at least one sideof the panel, the darkening layer configured to improve a contrast forviewing the light on a side of the dual-sided display that is notdarkened by the darkening layer.
 13. The dual-sided display of claim 1,wherein: the panel has multiple tiles, control circuitry of each tile isdisposed on a thin transparent electrical backplane of the tile, and thecontrol circuitry of each tile is disposed on a single side of thedisplay.
 14. The dual-sided display of claim 1, wherein: the panel hasmultiple tiles, control circuitry of each tile is disposed on a thintransparent electrical backplane of the tile, and the control circuitryof at least one tile is disposed on a different side of the display asthe control circuitry of at least one other tile.
 15. The dual-sideddisplay of claim 1, wherein: the panel has multiple tiles, and the tilesare configured to operate independently to selectively provide differentimages or aggregated to provide an extended display.
 16. The dual-sideddisplay of claim 1, wherein a backplane of the panel is formed from asilicon complementary metal-oxide semiconductor (CMOS).
 17. An arraycomprising a plurality of micro light-emitting diodes (microLEDs)configured to provide light to be viewed on opposing sides of the array,a distance between the microLEDs configured to provide visibilitythrough the array.
 18. The array of claim 17, further comprising: atransparent flexible substrate; and a transparent rigid substrateadhered to the transparent flexible substrate via an adhesive layer inwhich the array is encapsulated, wherein each microLED includes: ann-type semiconductor layer; a p-type semiconductor layer; an activeregion between the n-type semiconductor layer and the p-typesemiconductor layer; and a transparent contact disposed on each of then-type semiconductor layer and the p-type semiconductor layer.
 19. Thearray of claim 17, further comprising: a transparent flexible substrate;and a transparent rigid substrate adhered to the transparent flexiblesubstrate via an adhesive layer in which the array is encapsulated,wherein each microLED includes: an n-type semiconductor layer; a p-typesemiconductor layer; an active region between the n-type semiconductorlayer and the p-type semiconductor layer; at least one material selectedfrom materials including a transparent contact and a transparent coatingdisposed on each of the n-type semiconductor layer and the p-typesemiconductor layer; and a non-transparent contact disposed on a surfaceof one of the n-type semiconductor layer and the p-type semiconductorlayer opposite a surface of the one of the n-type semiconductor layerand the p-type semiconductor layer on which the transparent coating isdisposed, the non-transparent contact adjacent to the active region. 20.The array of claim 18, wherein the array is a sparse array and thedistance between the microLEDs in the array is substantially uniform.21. A display panel configured to display information, comprising: asparse array of micro light-emitting diodes (microLEDs) configured toprovide light to be viewed on opposing sides of the panel; and adarkening layer disposed on each side of the array, each darkening layerconfigured to provide selectable darkening to block light from exitingthe panel and configured to be independently activatable between atransparent mode and an opaque mode.
 22. The panel of claim 21, whereinthe array is disposed within a conformal transparent adhesive between atransparent backplane and a transparent substrate, the darkening layersdisposed on an opposite surface of the transparent backplane and atransparent substrate as the array.